Derivatives - Derivative Activity (Details) $ in Thousands	3 Months Ended
	Mar. 31, 2020 USD ($) institution	Mar. 31, 2019 USD ($)
Derivative Instruments and Hedging Activities Disclosure
(Gain) loss on derivative contracts	$ (10,226)	$ 209
Cash received on settlements	$ (4,087)	(5,078)
Number of counterparties to open derivative contracts | institution	2
Commodity derivative contracts
Derivative Instruments and Hedging Activities Disclosure
(Gain) loss on derivative contracts	$ (10,226)	209
Cash received on settlements	$ (4,087)	$ (5,078)